ACC/AHA 2002 Guideline Update for Exercise Testing: Summary Article

HomeCirculationVol. 106, No. 14ACC/AHA 2002 Guideline Update for Exercise Testing: Summary Article Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBACC/AHA 2002 Guideline Update for Exercise Testing: Summary ArticleA Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1997 Exercise Testing Guidelines) Committee Members Raymond J. Gibbons, MD, FACC, FAHA, Chair, Gary J. Balady, MD, FACC, FAHA, J. Timothy Bricker, MD, FACC, Bernard R. Chaitman, MD, FACC, FAHA, Gerald F. Fletcher, MD, FACC, FAHA, Victor F. Froelicher, MD, FACC, FAHA, Daniel B. Mark, MD, MPH, FACC, FAHA, Ben D. McCallister, MD, FACC, FAHA, Aryan N. Mooss, MBBS, FACC, FAHA, Michael G. O’Reilly, MD, FACC, William L. WintersJr, MD, FACC, FAHA, Raymond J. Gibbons, Task Force Members:, MD, FACC, FAHA, Chair, Elliott M. Antman, MD, FACC, FAHA, Vice Chair, Joseph S. Alpert, MD, FACC, FAHA, David P. Faxon, MD, FACC, FAHA, Valentin Fuster, MD, PhD, FACC, FAHA, Gabriel Gregoratos, MD, FACC, FAHA, Loren F. Hiratzka, MD, FACC, FAHA, Alice K. Jacobs, MD, FACC, FAHA, Richard O. Russell, MD, FACC, FAHA and Sidney C. SmithJr, MD, FACC, FAHA Committee Members Search for more papers by this author , Raymond J. GibbonsRaymond J. Gibbons Search for more papers by this author , Gary J. BaladyGary J. Balady Search for more papers by this author , J. Timothy BrickerJ. Timothy Bricker Search for more papers by this author , Bernard R. ChaitmanBernard R. Chaitman Search for more papers by this author , Gerald F. FletcherGerald F. Fletcher Search for more papers by this author , Victor F. FroelicherVictor F. Froelicher Search for more papers by this author , Daniel B. MarkDaniel B. Mark Search for more papers by this author , Ben D. McCallisterBen D. McCallister Search for more papers by this author , Aryan N. MoossAryan N. Mooss Search for more papers by this author , Michael G. O’ReillyMichael G. O’Reilly Search for more papers by this author , William L. WintersJrWilliam L. WintersJr Search for more papers by this author , Raymond J. GibbonsRaymond J. Gibbons Search for more papers by this author , Elliott M. AntmanElliott M. Antman Search for more papers by this author , Joseph S. AlpertJoseph S. Alpert Search for more papers by this author , David P. FaxonDavid P. Faxon Search for more papers by this author , Valentin FusterValentin Fuster Search for more papers by this author , Gabriel GregoratosGabriel Gregoratos Search for more papers by this author , Loren F. HiratzkaLoren F. Hiratzka Search for more papers by this author , Alice K. JacobsAlice K. Jacobs Search for more papers by this author , Richard O. RussellRichard O. Russell Search for more papers by this author and Sidney C. SmithJrSidney C. SmithJr Search for more papers by this author Originally published1 Oct 2002https://doi.org/10.1161/01.CIR.0000034670.06526.15Circulation. 2002;106:1883–1892The American College of Cardiology (ACC)/American Heart Association (AHA) Task Force on Practice Guidelines regularly reviews existing guidelines to determine when an update or full revision is needed. This process gives priority to areas where major changes in text, and particularly recommendations, are mentioned on the basis of new understanding or evidence. Minor changes in verbiage and references are discouraged.The ACC/AHA guidelines for exercise testing that were published in 1997 have now been updated. The full-text guidelines incorporating the updated material are available on the Internet (www.acc.org or www.americanheart.org) in both a version that shows the changes in the 1997 guidelines in strike-over (deleted text) and highlighting (new text) and a “clean” version that fully incorporates the changes.This article describes the 10 major areas of change reflected in the update in a format that we hope can be read and understood as a stand-alone document. The table of contents from the full-length guideline (see next page) indicates the location of these changes. Interested readers are referred to the full-length Internet version to completely understand the context of these changes. All new references appear in boldface type; all original references appear in normal type.Table of ContentsPreamble263 I.Introduction263Exercise Testing Procedure264General Overview264Indications and Safety265Equipment and Protocols265Exercise End Points265Interpretation of the Exercise Test265Cost and Availability265Clinical Context266II.Exercise Testing to Diagnose Obstructive Coronary Artery Disease266Rationale268Pretest Probability268Diagnostic Characteristics and Test Performance268Believability Criteria for Diagnostic Tests270Diagnostic Accuracy of the Standard Exercise Test270Confounders of Stress ECG Interpretation (Modification I)273ST-Segment Interpretation Issues273III.Risk Assessment and Prognosis in Patients With Symptoms or a Prior History of Coronary Artery Disease274Risk Stratification: General Considerations274Prognosis of Coronary Artery Disease: General Considerations274Risk Stratification With the Exercise Test (Modifications II, III, IV)275Use of Exercise Test Results in Patient Treatment280IV.After Myocardial Infarction (Modification V)280Exercise Test Logistics281Risk Stratification and Prognosis282Activity Counseling284Cardiac Rehabilitation285Summary285V.Exercise Testing Using Ventilatory Gas Analysis285VI.Special Groups: Women, Asymptomatic Individuals, and Postrevascularization Patients287Women287Diagnosis of Coronary Artery Disease in the Elderly289Exercise Testing in Asymptomatic Persons Without Known CAD (Modifications VI, VII)290Valvular Heart Disease (Modification VIII)293Exercise Testing Before and After Revascularization294Investigation of Heart Rhythm Disorders (Modification IX)296Evaluation of Hypertension (Modification X)NewVII.Pediatric Testing: Exercise Testing in Children and Adolescents297Differences Between Pediatric and Adult Testing297Exercise Testing for Specific Pediatric and Congenital Cardiac Problems298Appendixes302References303The ACC/AHA classifications, I, II, and III are used to summarize indications as follows:Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective.Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment.IIa: Weight of evidence/opinion is in favor of usefulness/efficacy.IIb: Usefulness/efficacy is less well established by evidence/opinion.Class III: Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful.In the original guideline, the committee did not rank the available scientific evidence in an A, B, or C fashion. The level of evidence is provided for the new recommendations appearing in the update. The weight of the evidence was ranked highest (A) if the data were derived from multiple randomized clinical trials that involved large numbers of patients and intermediate (B) if the data were derived from a limited number of randomized trials that involved small numbers of patients or from careful analyses of nonrandomized studies or observational registries. A lower rank (C) was given when expert consensus was the primary basis for the recommendation.The ACC/AHA Task Force on Practice Guidelines welcomes feedback on this update process and the format of this article. Please direct your comments to the Task Force c/o Dawn Phoubandith, American College of Cardiology or via e-mail ([email protected]).Modification IThe text in the 1997 guidelines that appeared under the major heading “Diagnosis” and the subheading “Influence of Other Factors on Test Performance” has been extensively reorganized. This began on page 272 (second column) of the original guidelines. New material regarding ST–heart rate and adjustment changes during and after exercise is reproduced below. New material on atrial repolarization and right chest leads appears in the full-text guidelines on the Internet.ST–Heart Rate AdjustmentSeveral methods of heart rate adjustment have been proposed to increase the diagnostic accuracy of the exercise ECG. The maximal slope of the ST segment relative to heart rate is derived either manually1 or by computer.2 A second technique, termed the ST/HR index, divides the difference between ST depression at peak exercise by the exercise-induced increase in heart rate.3,4 ST/HR adjustment has been the subject of several reviews since the last publication of these guidelines.5,6 The major studies that used this approach for diagnostic testing include Morise’s report7 of 1358 individuals undergoing exercise testing (only 152 with catheterization data) and the report by Okin et al8 considering heart rate reserve (238 controls and 337 patients with coronary disease). Viik et al considered the maximum value of the ST-segment depression/heart rate (ST/HR) hysteresis over a different number of leads for the detection of coronary artery disease (CAD).9 The study population consisted of 127 patients with coronary disease and 220 patients with a low likelihood of the disease referred for an exercise test. Neither the study by Okin et al or that by Viik et al considered consecutive patients with chest pain, and both had limited challenge. Because healthy patients have relatively high heart rates and sick patients have low heart rates, which leads to a lower ST/HR index in normals and a higher index in sicker patients, the enrollment of relatively healthy patients in these studies presents a limited challenge to the ST/HR index. Likewise, the Morise study7 had a small number of patients who underwent angiography. The only study with neither of these limitations was QUEXTA.10 This large multicenter study followed a protocol to reduce workup bias and was analyzed by independent statisticians. The ST/HR slope or index was not found to be more accurate than simple measurement of the ST segment. Although some studies in asymptomatic (and therefore very low likelihood) individuals have demonstrated additional prognostic value with ST/HR adjustment, these data are not directly applicable to the issue of diagnosis in symptomatic patients.11,12 Nevertheless, one could take the perspective that the ST/HR approach in symptomatic patients has at least equivalent accuracy to the standard approach. Although not yet validated, there are situations in which the ST/HR approach could prove useful, such as in rendering a judgment concerning certain borderline or equivocal ST responses, eg, ST-segment depression associated with a very high exercise heart rate.In asymptomatic patients, in MRFIT, significant concentration of cardiac risk was associated with an abnormal ST/HR index but not with abnormal standard exercise test criteria as judged by computer interpretation.12 Compared with patients in the usual care group, cardiac events were reduced in the risk factor modification group when the exercise test was positive according to the ST/HR index.13Modification IIThese revised recommendations (see top of page) incorporate new recommendations for risk stratification in patients with unstable angina. The table of recommendations originally appeared at the beginning of the heading on “Risk Assessment” on page 274 (first column).Modification II1997 Exercise Testing Guideline Recommendation2002 Exercise Testing Guideline RecommendationClass IClass I 1. Patients undergoing initial evaluation with suspected or known CAD. Specific exceptions are noted below in Class IIb. 1. Patients undergoing initial evaluation with suspected or known CAD, including those with complete right bundle-branch block or less than 1 mm of resting ST depression. Specific exceptions are noted below in Class IIb. 2. Patients with suspected or known CAD previously evaluated with significant change in clinical status. 2. Patients with suspected or known CAD, previously evaluated, now presenting with significant change in clinical status. 3. Low-risk unstable angina patients (see Table 17) 8 to 12 hours after presentation who have been free of active ischemic or heart failure symptoms. (Level of Evidence: B) 4. Intermediate-risk unstable angina patients (see Table 17) 2 to 3 days after presentation who have been free of active ischemic or heart failure symptoms. (Level of Evidence: B)Class IIaClass IIa 1. Intermediate-risk unstable angina patients (see Table 17) who have initial cardiac markers that are normal, a repeat ECG without significant change, and cardiac markers 6 to 12 hours after the onset of symptoms that are normal and no other evidence of ischemia during observation.(Level of Evidence: B)Class IIbClass IIb 1. Patients with the following ECG abnormalities 1. Patients with the following resting ECG abnormalities • Pre-excitation (Wolff-Parkinson-White) syndrome • Pre-excitation (Wolff-Parkinson-White) syndrome • Electronically paced ventricular rhythm • Electronically paced ventricular rhythm • Greater than 1 mm of resting ST depression • 1 mm or more of resting ST depression • Complete left bundle-branch block • Complete left bundle-branch block or any interventricular conduction defect with a QRS duration greater than 120 ms 2. Patients with a stable clinical course who undergo periodic monitoring to guide treatment. 2. Patients with a stable clinical course who undergo periodic monitoring to guide treatment.Class IIIClass III 1. Patients with severe comorbidity likely to limit life expectancy and/or candidacy for revascularization. 1. Patients with severe comorbidity likely to limit life expectancy and/or candidacy for revascularization. 2. High-risk unstable angina patients (see Table 17). (Level of Evidence: C)Modification IIIThis revised text incorporates new published evidence on elderly patients, heart-rate responses during and after exercise, and systolic blood pressure responses during and after exercise. It replaces material in the original text that appeared under the major heading “Risk Stratification” and the subheading “Nonacute Coronary Artery Disease” beginning on page 278 (second column).The value of exercise treadmill testing for prognostic assessment in elderly subjects has been described in the Olmstead County, Minnesota, cohort followed by the Mayo Clinic.14 As expected, the elderly patients (aged greater than or equal to 65 years) had more comorbidity and achieved a lower workload than their younger counterparts. They also had a significantly worse unadjusted survival. Workload expressed as metabolic equivalents (METs) was the only treadmill variable associated with all-cause mortality in both groups (adjusting for clinical prognostic variables), whereas both workload and exercise angina were associated with cardiac events (death plus myocardial infarction) in both groups. A positive ST response was not prognostic in the older patients when tested as a binary variable. Quantitative ST-segment deviation with exercise was apparently not available in this cohort, and the Duke Treadmill Score was not computed in this study.Morrow and colleagues15 developed a prognostic score using data from 2546 patients from Long Beach Veterans Administration Hospital. This score includes 2 variables in common with the Duke treadmill score (exercise duration or the MET equivalent and millimeters of ST changes) and 2 different variables (drop in exercise systolic blood pressure below resting value and history of congestive heart failure [CHF] or use of digoxin [Dig]). The score is calculated as follows:5 × (CHF/Dig [yes=1; no=0]) + exercise-induced ST depression in millimeters + change in systolic blood pressure score − METs,where systolic blood pressure=0 for an increase greater than 40 mm Hg, 1 for an increase of 31 to 40 mm Hg, 2 for an increase of 21 to 30 mm Hg, 4 for an increase of 0 to 11 mm Hg, and 5 for a reduction below standing systolic preexercise blood pressure. With this score, 77% of the Long Beach Veterans Administration Hospital population were at low risk (with less than 2% average annual mortality), 18% were at moderate risk (average annual mortality, 7%), and 6% were at high risk (average annual mortality, 15%).Several studies have highlighted the prognostic importance of other parameters from the exercise test. Chronotropic incompetence, defined as either failure to achieve 80% to 85% of the age-predicted maximum exercise heart rate or a low chronotropic index (heart rate adjusted to MET level), was associated with an 84% increase in the risk of all-cause mortality over a 2-year follow-up in 1877 men and 1076 women who were referred to the Cleveland Clinic for symptom-limited thallium treadmill testing.16,17 The Cleveland Clinic investigators have also demonstrated the prognostic importance of an abnormal heart rate recovery pattern after exercise testing. Defined as a change from peak exercise heart rate to heart rate measured 2 minutes later of less than or equal to 12 beats per minute, an abnormal heart rate recovery was strongly predictive of all-cause mortality at 6 years in 2428 patients referred for thallium exercise testing.18 Similar trends have been suggested for a delayed systolic blood pressure response after exercise, defined as a value greater than 1 for systolic blood pressure at 3 minutes of recovery divided by systolic blood pressure at 1 minute of recovery. This finding was associated with severe CAD in a study of 493 patients at the Cleveland Clinic who had both symptom-limited exercise testing and coronary angiography (within 90 days).19 In a study of 9454 consecutive patients, most of whom were asymptomatic, the Cleveland Clinic investigators reported that abnormal heart rate recovery and the Duke treadmill score were independent predictors of mortality.20 Further work is needed to define the role of chronotropic incompetence, abnormal heart rate recovery, and delayed blood pressure response in the risk stratification of symptomatic patients relative to other well-validated treadmill test parameters.In patients who are classified as low risk on the basis of clinical and exercise testing information, there is no compelling evidence that an imaging modality adds significant new prognostic information to a standard exercise test. In this regard, a distinction should be made between studies that show a statistical advantage of imaging studies over exercise ECG alone and studies that demonstrate that the imaging data would change practice (eg, by shifting patients from moderate- to low- or high-risk categories). Because of its simplicity, lower cost, and widespread familiarity in its performance and interpretation, the standard treadmill ECG is the most reasonable exercise test to select in men with a normal resting ECG who are able to exercise. In patients with an intermediate-risk treadmill score, myocardial perfusion imaging appears to be of value for further risk stratification.21 Patients with an intermediate-risk treadmill score and normal or near-normal exercise myocardial perfusion images and normal cardiac size are at low risk for future cardiac death and can be managed medically.22Modification IVThis revised text, revisedTable 17, and new Table 17a incorporate new published evidence regarding patients with unstable angina and the use of treadmill testing in chest pain centers. They replace text and Table 17that originally appeared under the major heading “Risk Stratification” and the subheading “Unstable Angina,” beginning on page 280 (first column).Revised TABLE 17. Short-Term Risk of Death or Nonfatal Myocardial Infarction in Patients With Unstable AnginaHigh RiskIntermediate RiskLow RiskMI indicates myocardial infarction; CABG, coronary artery bypass graft; CAD, coronary artery disease; NTG, nitroglycerin; CCSC, Canadian Cardiovascular Society Classification; MR, mitral regurgitation; ECG, electrocardiography; and BBB, bundle-branch block.Estimation of the short-term risks of death and nonfatal cardiac ischemic events in unstable angina is a complex multivariable problem that cannot be fully specified in a table such as this. Therefore, the table is meant to offer general guidance and illustration rather than rigid algorithms. Adapted from Agency for Health Care Policy and Research Clinical Practice Guideline No. 10, Unstable Angina: Diagnosis and Management, May 1994.FeatureAt least 1 of the following features must be present:No high-risk feature but must have 1 of the following:No high- or intermediate-risk feature but may have any of the following features:HistoryPrior MI, peripheral or cerebrovascular disease, or CABG or prior aspirin useCharacter of painProlonged ongoing (greater than 20 minutes) rest painProlonged (greater than 20 minutes) rest angina, now resolved, with moderate or high likelihood of CADNew-onset or progressive CCSC III or IV angina in the past 2 weeks with moderate or high likelihood of CADRest angina (less than 20 minutes) or relieved with rest or sublingual NTG)Clinical findingsPulmonary edema, most likely related to ischemiaAge older than 70 yearsNew or worsening MR murmurS3 or new/worsening ralesHypotension, bradycardia, tachycardiaAge older than 75 yearsECG findingsAngina at rest with transient ST changes greater than 0.05 mVT-wave inversions greater than 0.2 mVNormal or unchanged ECG during an episode of chest discomfortBBB, new or presumed newPathological Q wavesSustained ventricular tachycardiaBiochemical cardiac markersElevated (eg, troponin T or I greater than 0.1 mg/mL)Slightly elevated (eg, troponin T greater than 0.01 but less than 0.1 mg/mL)NormalTABLE 17A. Summary of Studies Using Exercise ECG Testing in Chest Pain CentersGroup (year)ReferenceNo. of SubjectsFollow-Up PeriodExercise ECGAdverse Events*% Disease PrevalenceClinical OutcomeSLM indicates symptom-limited maximum end point; APMHR, age-predicted maximum heart rate end point.*Death or myocardial infarction.†With respect to diagnosis if admitted, and 30-day follow-up on all patients.‡With respect to reference diagnosis from admission of all patients.§Included 70 patients (25%) with a history of coronary heart disease.¶Comparison of those admitted to hospital vs chest pain center.Reprinted with permission from Stein et al, Circulation. 2000;102:1463–1467.25Tsakonis et al (1991)31286.1 moModified Bruce (SLM)00Exercise testing was safeKerns et al (1993)32326 moBruce (APMHR)00Exercise testing was safeReduced cost vs admissionGibler et al (1995)29101030 dBruce (SLM)05Sensitivity=29%Specificity=99.4%Positive predictive value=44%†Negative predictive value=98.7%†Gomez et al (1996)3350, plusNoneCornell (SLM)06No difference in clinical outcome50 controlsReduced cost vs admitted controlZalenski et al (1998)34317None; patients admitted for reference diagnosisModified Bruce09.5Sensitivity=90% Specificity=50%‡ Negative predictive value=98%‡Polanczyk et al (1998)35276§6 moModified Bruce025Sensitivity=73%Specificity 74%Negative predictive value=98%Farkouh et al (1998)304246 moNot specified0Intermediate-risk patients were studiedNo difference in clinical outcomes¶Reduced cost vs admitted controlPatients With Acute Coronary SyndromeAcute coronary syndrome (unstable angina or acute myocardial infarction) represents an acute phase in the life cycle of the patient with chronic coronary disease. It may be a presenting feature or may interrupt a quiescent phase of clinically manifested disease. The natural history of ACS involves progression to either death or myocardial infarction on the one hand or return to the chronic stable phase of CAD on the other. These events typically play out over a period of 4 to 6 weeks. Thus, the role and timing of exercise testing in ACS relates to this acute and convalescent period.The ACC/AHA 2002 Guideline Update for the Management of Patients With Unstable Angina and Non–ST-Segment Elevation Myocardial Infarction has been published.23 A clinical risk stratification algorithm useful for selecting the initial management strategy is seen in the revised Table 17. Patients are separated into low-, intermediate-, or high-risk groups based on history, physical examination, initial 12-lead ECG, and cardiac markers. (Note that this table is meant to be illustrative rather than comprehensive or definitive.) Low-risk patients, who include patients with new-onset or progressive angina with symptoms provoked by walking 1 block or 1 flight of stairs, in this scheme can typically be treated on an outpatient basis. Most intermediate-risk patients can be cared for in a monitored hospital bed, whereas high-risk patients are typically admitted to an intensive care unit.Exercise or pharmacological stress testing should generally be an integral part of the evaluation of low-risk patients with unstable angina who are evaluated on an outpatient basis. In most cases, testing should be performed within 72 hours of presentation. In low- or intermediate-risk patients with unstable angina who have been hospitalized for evaluation, exercise or pharmacological stress testing should generally be performed unless cardiac catheterization is indicated. In low-risk patients, testing can be performed when patients have been free of active ischemic or heart failure symptoms for a minimum of 8 to 12 hours.23 Intermediate-risk patients can be tested after 2 to 3 days, but selected patients can be evaluated earlier as part of a carefully constructed chest pain management protocol (see section on chest pain centers below). In general, as with patients with stable angina, the exercise treadmill test should be the standard mode of stress testing in patients with a normal resting ECG who are not taking digoxin.A majority of patients with unstable angina have an underlying ruptured plaque and significant CAD. Some have a ruptured plaque without angiographically significant lesions in any coronary segment. Still others have no evidence of a ruptured plaque or atherosclerotic coronary lesions. Little evidence exists with which to define the safety of early exercise testing in unstable angina.24,25 One review of this area found 3 studies covering 632 patients with stabilized unstable angina who had a 0.5% death or myocardial infarction rate within 24 hours of their exercise test.25The limited evidence available supports the use of exercise testing in acute coronary syndrome patients with appropriate indications as soon as the patient has stabilized clinically. Larsson and colleagues26 compared a symptom-limited predischarge (3 to 7 days) exercise test with a test performed at 1 month in 189 patients with unstable angina or non–Q-wave infarction. The prognostic value of the 2 tests was similar, but the earlier test identified additional patients who would experience events during the period before the 1-month exercise test. In this population, these earlier events represented one half of all events occurring during the first year.The Research on Instability in Coronary Artery Disease (RISC) study group27 examined the use of predischarge symptom-limited bicycle exercise testing in 740 men admitzted with unstable angina (51%) or non–Q-wave myocardial infarction (49%). The major independent predictors of 1-year infarction-free survival in multivariable regression analysis were the number of leads with ischemic ST-segment depression and peak exercise workload achieved.In 766 unstable angina patients enrolled in the FRISC study between 1992 and 1994 who had both a troponin T level and a predischarge exercise test, the combination of a positive troponin T and exercise-induced ST depression stratified patients into groups with a risk of death or MI ranging from 1% to 20%.28 In 395 women enrolled in FRISC I with stabilized unstable angina who underwent a symptom-limited stress test at days 5 to 8, risk for cardiac events in the next 6 months could be stratified from 1% to 19%. Important exercise variables included not only ischemic parameters such as ST depression and chest pain but also parameters that reflected cardiac workload.Chest Pain CentersOver the last decade, an increasing experience has been gained with the use of exercise testing in emergency department chest pain centers (see new Table 17a).25 The goal of a chest pain center is to provide rapid and efficient risk stratification and management for chest pain patients believed to possibly have acute coronary disease. A variety of physical and administrative setups have been used for chest pain centers in medical centers across the country; review of these details is beyond the scope of these guidelines. In most of the published series, exercise testing has been reserved for the investigation of patients who are low risk on the basis of history and physical examination, 12-lead ECG, and serum markers. In the study by Gibler et al,29 1010 patients were evaluated by clinical examination, 9 hours of continuous ST monitoring, serial 12-lead ECGs, serial measurement of creatine kinase-MB, and resting echocardiograms. Patients without high-risk markers on the basis of this evaluation (78%) underwent a symptom-limited Bruce exercise ECG test. There were no adverse events from the testing, and the authors estimated a 5% prevalence of CAD in the tested population. These results are generally representative of the results in the approximately 2100 chest pain patients who have undergone exercise testing as part of a chest pain center protocol report (see new Table 17a).25 The prevalence of CAD is extremely low in such chest pain pati